1. Field of Invention
The invention relates to a method of finding a data-recorded area and an unrecorded area, and more particularly to a method of finding a data-recorded area and an unrecorded area by identifying whether data is recorded at a position of a data layer according to a reflecting intensity of the data layer on an optical disk.
2. Related Art
A conventional optical storage medium player (disk player) does not have the ability of tracking on an unrecorded area of an optical disk. Thus, it is necessary to ensure the optical head after focus is positioned in a data-recorded area when the tracking control is to be performed.
FIG. 1 is a schematic illustration showing a conventional method of positioning an optical head. Referring to FIG. 1, an optical disk 11 includes a lead-in area, a data area, a lead-out area and an unrecorded area. A control unit 12 transfers a driving signal to a driving circuit 13, and then the driving circuit 13 drives a motor 14 to control movement of an optical head 16. In the prior art, a limit switch 15 on an optical reading mechanism is usually utilized for homing the optical reading mechanism, then moves the optical head 16 toward the outer ring according to the experimental driving voltage and counts the predetermined time after escaping from the limit switch, and then stops the optical head 16 for positioning. Thus, the prior art has to verify various optical disks and various optical reading mechanisms in advance to overcome the variations.
In addition, in correspondence with the function of a disk recorder, which enables the user to use the whole recordable optical storage disk, or in order to allow data to be recorded again, the option of enabling the user to select whether to finalize the optical disk every time when the data is recorded is induced. If the user selects to finalize the optical disk, the file system, the lead-in area and the lead-out area will be recorded so that the optical disk can be widely compatible with various optical storage medium players (disk players). If the user does not select to finalize the optical disk, the file system, the lead-in area and the lead-out area will not be completely recorded. Thus, most of the optical disks only can be played in the player capable of recording the data.
When the conventional optical storage medium player is reading a recordable optical storage medium (CD-R, CD-RW, DVD+R/+RW, DVD-R/-RW or the like), the optical head has to focus on the data-recorded area so that a correct track-crossing signal (referring to FIG. 1) can be generated. If the optical head is focused on the data layer, but the area has no recorded signal, the conventional player tracking control system cannot generate the correct track-crossing signal according to the area having no recorded data. Thus, the focus point of the optical head can not be fixed on the data track to cause the tracking control system invalid. In the player with the recording function, the architecture and the front end signal processing mechanism of the optical head of the player are different from those players used for purely playing the optical disk. Thus, the track-crossing signal still can be generated in the blank area, so the optical head still can be fixed on the data track without recorded data.
In order to prevent the tracking problem in the prior art, the limit switch and a predetermined period are adopted for performing the positioning. However, the recordable optical storage medium may have a little data recorded by the user, so the area occupied by the lead-in area, the data area and the lead-out area is very small, as shown in FIG. 2, which is a schematic illustration showing a finalized recordable optical disk medium having a little data. In another aspect, the user may use a recordable optical player to record the data but does not finalize the optical disk, so only a few tracks are recorded in the data of the lead-in area. When the data of the data area is very small, the area for the tracking control may be smaller than 1 mm, as shown in FIG. 3, which is a schematic illustration showing a recordable optical disk medium, which only records a little data and is not finalized. In this case, using the conventional method to position the initial position of the optical head is very difficult. Because frictional forces on the optical reading mechanism are not uniform, and the recorded initial positions on the optical disks may be slightly different from one another, or the driving circuit itself may have drift and difference. Thus the read failure may occur when the conventional method is used to read the optical disk.
In addition, the non-finalized recordable optical storage medium does not record the file system and the complete lead-in information, so the conventional read-only player cannot play this recordable optical storage medium.